Interpretive Summary: Bermudagrass is one the most troublesome weeds in Louisiana sugarcane. Management strategies were compared over a four-year sugarcane cropping cycle at two locations. These management strategies included tillage frequency, post-harvest residue (leaf mulch) removal, and herbicide usage. Three tillage frequencies were compared: conventional, where sugarcane row-sides were tilled four times each spring; reduced, where row-sides were tilled twice each spring; and no-till, where sugarcane was not tilled after planting during the complete cropping cycle. Three post-harvest residue management practices were compared: complete removal, leaf mulch was burned soon after harvest each year; partial removal, leaf mulch was brushed off the row top soon after harvest each year, and no removal, leaf residue was left in place following harvest. Three herbicide usages were compared: broadcast, where complete herbicide application coverage of both row top and middles was used, banded, where only the row top received an herbicide application; and no herbicide usage. Reducing tillage frequency increased the amount of bermudagrass in the sugarcane with the greatest amount of bermudagrass in areas where no-till was used. Reducing the number of tillage applications from four to two increased the amount of bermudagrass in sugarcane only when used in combination with banded herbicide application. Removal of leaf mulch did not affect the amount of bermudagrass in sugarcane. In the first year of the sugarcane cropping cycle, the plant-cane year, sugarcane yields were only reduced when no herbicide were applied or with banded herbicide application in combination with no-till at one of two locations. In the second, third, and fourth years, or ratoon crops, reducing herbicide usage by banding herbicide applications resulted in reduced cane yields only when used in combination with no-till. Tillage alone, without the use of herbicides always resulted in lower sugarcane yields. When using no-till during the entire crop cycle, total cane yield was reduced 11% when herbicides were broadcast applied, 15% when herbicides were banded, and 25% when no herbicides were applied compared with conventional tillage. Even though removal of leaf mulch did not affect bermudagrass infestation, failure to remove leaf mulch reduced sugarcane yields by an average of 5 to 10% compared with complete removal by burning. Reducing tillage in sugarcane appears to be a practical way of reducing production costs. However, increased herbicide usage may be needed to reduce competition from weeds such as bermudagrass. Partial or complete removal of leaf mulch is recommended as this did not affect the amount of bermudagrass in sugarcane and not removing leaf mulch did result in lower sugarcane yield.

Technical Abstract:
Bermudagrass is a difficult perennial weed to manage in Louisiana sugarcane. Research was conducted to compare interrow tillage practice, postharvest residue management, and herbicide placement on bermudagrass proliferation and sugarcane yield. Tillage frequencies included conventional (four tillage operations per season), reduced (two tillage operations), and no-till. Residue management practices included removal by burning, sweeping from row top into the wheel furrow, and not removed. Spring herbicide placement treatments included broadcast, banded, or no herbicide application. With conventional tillage, broadcast and banded herbicide applications resulted in similar bermudagrass cover in the first and second ratoon crops, but bermudagrass cover was greater when using banded applications (22%) compared with broadcast application (15%) in the third-ratoon crop. Bermudagrass cover was greatest with no-till. When herbicides were banded, bermudagrass cover was greater in reduced tillage than conventional tillage in all three ratoon crops. Postharvest residue management did not affect bermudagrass ground cover. In plant cane, sugarcane yields were lowest when herbicide was not applied. In ratoon crops, sugarcane and sugar yield were reduced when herbicide was not applied regardless of tillage practice. Cane and sugar yield were generally equal when comparing reduced and conventional tillage. Total sugarcane yield (4 crop yr) for the no-till program was reduced 11, 15, and 25%, respectively, when herbicides were broadcast, banded, and when herbicide was not applied, compared with conventional tillage. Failure to remove residue reduced sugarcane yield by 5, 7, and 10% in first, second, and third ratoons, respectively, compared with burning. Eliminating unnecessary tillage practices can increase profitability of sugarcane through reduced costs, but it will be imperative that herbicide programs be included to provide adequate bermudagrass control and that postharvest residue is removed to promote maximum sugar yield.